Venus and Mercury close-ups

On 5 February 1974 the Mariner 10 space probe passes by of our sister planet Venus. Venus is close to the size of the earth, but covered in thick clouds and deep mystery. Mariner 10 passes at 5790 km and takes the best photos up till now, showing new and important details. The needs of exploring and learning are great drivers for us human beings, this mission takes it to new limits.

Venusian cloud layers in UV/optical bands.

Mariner 10 space probe

Mariner 10 has another mission, to pass by Mercury. No space craft has been there before, and no probe has ever visited two planets.  Mercury is the closest planet to the Sun, and a difficult destination. So the mission has been planned in great detail. NASA uses a new technique, gravitational slingshot. By taking advantage of Venus’ gravitational energy the probe accelerates as it comes closer, and when it passes by it decelerates. By this the probe’s speed and angle can be changed. It was first used by the Russian Luna 3 in 1959 photographing the far side of the moon. But this is the first time it is tested between planets.

NASA 1972 plan for Mariner 10 to use the gravitational pull to "slingshot" itself towards Mercury.

The Americans succeed, and Mariner 10 heads for Mercury. It reaches the destination on 29 March and sends back moon-like images. It returns twice and cover close to half the planets surface. The images are the best until the next probe “Messenger” comes by over 30 years later. After end of mission in 1975 it continues in orbit around the sun, and it is probably still out there, as the chance of having collided with an object is very slim.

The gravitational slingshot technique is used on Voyager 1 and 2 in the late 1970s in their great tours on the outer gas giant planets of the Solar system. Voyager 1 is now the farthest human made object from us, more than 19.000 million km away from us. That equals 127 times the distance from the sun to the earth. The orbit of these planets makes it impossible to use the gravitational slingshot until the middle of the 22 Century.

Thousands of images of Mercury were collected during Mariner 10, covering about half the planet.

 

Stamp of probe in 1975.

Sources and more information

http://history.nasa.gov/SP-424/ch5.htm
http://history.nasa.gov/SP-424/ch6.htm
http://photojournal.jpl.nasa.gov/spacecraft/Mariner%2B10
http://www.jpl.nasa.gov/missions/mariner-10/

I am open to your comments and proposals.
Regards
Bjarte Bjørsvik